Section 19: Ecosystem Essentials

SLOs: ecosystem components, abiotic and biotic factors, survival and stability.


Lesson 1:

Instruction

The existence of the biosphere, the region of Earth where life exists, is only possible because of the interactions between the atmosphere, hydrosphere, and lithosphere.  These interactions allow for conditions which can sustain diverse forms of life.  Ecology is the study of the relationships between biotic forms and their environments (ecosystems); while biogeography consists of the study of distributions of living things.  To understand biotic properties, it is necessary to know a few key terms that describe ecosystem features.  A community, or assemblage of populations (the same species within a specific range), is the first subdivision within an ecosystem.  The type of environment in which a population or community lives is called a habitat.  The function of each individual, population, species, or community is termed a niche.  A few of the relationships between organisms (living beings) are classified as competition (two individuals needing the same resources), predation (one individual needing the resources of another individual), symbiotic (two individuals helping each other survive) and parasitic (one individual eventually using the resources of and killing another individual) interactions.  The important thing to remember is that all living beings rely on other organisms and specialized environments for survival.            

Photos and Images
 (competitive relationship between surf grass and ice plant)     (predatory relationship between a sea gull and a red crab)

 

Quiz

Place the follow words in the correct order as determined by wide ranging to narrow ranging ecosystem components: community, individual, ecosystem, population, species.

 


Lesson 2:

Instruction

Abiotic and biotic factors are both ecosystem components.  Abiotic components of an ecosystem include light, water, temperature, climate, and specific gases.  The carbon/oxygen and nitrogen cycles exemplify the utility of abiotic components.  Flora photosynthesis/respiration and human activities are the most influential in the carbon/oxygen cycle.  Flora (plants and trees) utilize carbon to survive through photosynthesis and emit oxygen as a byproduct through respiration.  Humans intake oxygen, but currently create mass amounts of carbon through exhalation, fossil fuel mining and combustion, burning of forests for agricultural lands, industrial waste, so on and so forth.  Flora, fauna, and nitrogen-fixing bacteria all manipulate the nitrogen cycle.  All biotic material that dies goes through a process of decay, much of which is done by bacteria.  Thus, these living things require one another to balance environmental conditions for overall survival of their own species.  The food web demonstrates how this works.  The food web is structured with consumers on top, producers on the bottom, and decomposer (beings that facilitate recycling materials left by the aforementioned groups after death) all around.  Transferred energy from one group to another comprises the global food chain.  An example of a food web/chain is illustrated below.          

Photos and Images

 
 (an example food web)
(star fish)  (garibaldi fish)  (brown kelp)  (common dolphin)   (purple urchin)

 

Quiz

Given the photographs above, create a food web with the organisms shown.

 


Lesson 3:

Instruction

Survival is the goal of all life forms.  When ecosystems are stable, there are few disturbances and changing conditions.   However, ecosystems become unstable very quickly when disturbances and changing conditions are prevalent.  Death and change are therefore inevitable themes that accompany life.  Succession is the replacement of older life forms with newer forms of life in an ecosystem.  Speciation (the creation of a new species) and evolution (the changing of one species into another over time) account for the success of these newer forms of life.  Many biologists speculate that biodiversity (the diverse array of species in an ecosystem) is a necessity of survival.  If there are more different types of species, with different habitat needs and niches; then the entire community within an ecosystem has a better chance of risk distribution and, thus, survival.       

Photos and Images
    (diversity on land)          (diversity at sea) 

Quiz

There is a diverse array of marine organisms within Ventura County ocean waters.  Why should marine diversity in the Santa Barbara Channel be preserved?   


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2006 Jessica Douglas